The present invention relates to a method of improving the electrical conductivity of a molding article of resin, a method of coating a molding article of resin, and a coating composition.
The conventional method of coating a molding article of resin, for example, comprises coating an electrically conductive primer containing an inorganic conductive substance, e.g. conductive carbon black, graphite, or the like, on the surface of a polypropylene article to impart electrical conductivity to said surface and then carrying out electrostatic coating as described in JP-A-06165966.
However, as pointed out in JP-A-06165966, an inorganic conductive substance such as carbon black or graphite must be added in a substantial amount in order that it may be evenly and thoroughly distributed in the surface of the polypropylene article. Therefore, the technology has drawbacks in terms of the dispersion stability of the electrically conductive substance and the cost of production.
Recently disclosed is a method which comprises kneading a nitrogen-containing compound into the molding resin, molding the resultant composition, and subjecting the surface of the molding to low pressure plasma treatment (JP-A-07173308).
However, because the plasma treatment must be a batch operation for low pressure, the method is not adaptable to continuous production and is poor in commercial productivity.